Do I have to be careful during fertile days when using Mirena or Levosert?

Hello. Is it necessary to be careful when having a Mirena or Levosert insert during fertile days? Does the insole protect the insole equally throughout the cycle. I have a jyz insole half a year. And all the time there were regular every 28 days such scant bleeding . Last month it errs by a week and even more scant. Is it possible that these bleeding/ spotting disappears completely by the end of the application of the greetings